Other mistake: At the airport, after Deathstroke shoots his rifle, Garth (Aqualad) reacts to hearing the shot, turns around, and is then hit by the bullet. However, the bullet is traveling faster than sound and should have hit Garth (or Donna) before he heard the shot.
Other mistake: Conner's T-shirt never gets a bullet hole in it despite being shot in the chest. For example, we see him block 3 bullets with his body when saving Mr. Luthor. Nothing of his powers suggest he's generating a force field.
Revealing mistake: When the assistant gets thrown into the wall by the brain controlled Gar-tiger, there are already marks on the point of impact, from previous takes.
Plot hole: Cadmus sets a brain-controlled Connor loose in public, without apparently remotely considering the possibility that anything might go wrong. When he regains control all they've got is a few goons onsite armed with regular ammunition - what did they think that would achieve? They know exactly what he's capable of. Either have kryptonite ammo or don't bother having anyone there at all.
Bruce Wayne - S2-E7
Character mistake: After Jason falls from the skyscraper and is saved by Conner, he suffers some sort of PTSD. It is very hard to believe that a guy who fights crime all the time and fights people wanting to kill him so often (which includes Deathstroke beating and stabbing him like it was nothing) magically starts to suffer from PTSD just because he almost fell from a building. It doesn't make sense and feels forced.
Suggested correction: There was a lot more to the storyline than "some sort of PTSD." Of course, that kind of psychological trauma often doesn't make sense. Why would one veteran experience it and not another soldier who experienced the same thing. And he didn't "almost fell", he did fall off the building. If Conner wasn't there, he probably wouldn't have survived. He had never experienced failure in that manner either.
Bruce Wayne - S2-E7
Other mistake: Dick shoots into the bathtub to scare information out of the guy taking a bath. Three shots splash up - trouble is from the angle he was shooting at, very shallow, those bullets would have smashed through the other side of the bath, but nothing happens.